Redirective dual array antenna

ABSTRACT

Two circularly symmetrical concentric phase-steerable antenna arrays, scaled 3/2 in proportion to the wavelength at which each is designed to operate, have homologous radiators arranged in rings symmetrical about the common center. The radii of successive rings in a given array are 2.5, 4.75, and 5.75 times the radius of the innermost ring; the angular spacing of the radiators in each ring, beginning with the innermost, is 72*; 24*; 12.4*; and 10.28*. Each receiving radiator is tied to its homologous transmitting radiator through a network which corrects the phase of the received information band by reference to a receiving phase signal transmitted from the transmitting station, then further corrects the phase of the thus corrected information band by reference to a transmitting phase signal transmitted from the receiving station, and converts the thus doubly corrected information band to the transmitting frequency. As a result of the double phase correction, the frequency-converted information band is phase-steered to the receiving station.

Unite ttes Ptent Thomas 51 .luly 25, 1972 REDCTIVE DUAL ANTENNA RichardK. Thomas, Wayne, Pa.

[73] Assignee: General Electric Company [22] Filed: July 28, 1969 [21]Appl. No.: 845,198

[72] Inventor;

Primary Examiner-Richard A. Farley Assistant Examiner-Richard E. BergerAttorney-Allen E. Arngott, William G. Becker, Henry W. Kaufmann, JosephB. Forman, Frank L. Neuhauser and Oscar B. Waddell 57 ABSTRACT Twocircularly symmetrical concentric phase-steerable antenna arrays, scaled3/2 in proportion to the wavelength at which each is designed tooperate, have homologous radiators arranged in rings symmetrical aboutthe common center. The radii of successive rings in a given array are2.5, 4.75, and 5.75 times the radius of the innermost ring; the angularspacing of the radiators in each ring, beginning with the innermost, is72; 24; 12.4; and 10.28. Each receiving radiator is tiedto itshomologous transmitting radiator through a network which corrects thephase of the received information band by reference to a receiving phasesignal transmitted from the transmitting station, then further correctsthe phase of the thus corrected information band by reference to atransmitting phase signal transmitted from the receiving station, andconverts the thus doubly corrected information band to the transmittingfrequency. As a result of the double phase correction, thefrequency-converted information band is phase-steered to the receivingstation.

1 Claim, 2 Drawing Figures REDIRECTIVE DUAL AY ANTENNA BACKGROUND OF THEINVENTION 1. Field of the Invention This invention pertains tophase-steerable antennas.

2. Description of the Prior Art It is well known in the art to providephase-steerable directional antenna systems in which the direction ofthe main lobe of the antenna is controlled at will by altering therelative phase differences produced by the interconnection of variousparts of the radiating system. This practice has the advantage that beamdirection may be altered without the mechanical complications inherentin rotating the complete physical structure of an antenna. An oldexample of such a system, in which mechanical motion is used to producethe phase change requisite to cyclical scanning, is the AN/APQ-7 radarequipment described in Radar System Engineering", edited by L. N.Ridenour, 1947, McGraw-Hill Book Company, New York City, N. Y., pages291-295. However, the possibility of using purely electrical means toproduce phase changes has been exploited in later devices.

Phase-steering of linear arrays is relatively simple, since the phasedifference between any two successive equally-spaced radiators will bethe same, and a plurality of identical controllable phase-shiftingelements in cascade may be employed.

The use of phase-steering in circular arrays creates a marked problem inthat the phase differences between adjacent equally spaced elements arenot constant, but a somewhat complicated function of the locations ofthe elements in azimuth relative to the array center. This complicationeliminates the simple phase-steering techniques which are available foruse with linear arrays.

SUMMARY OF THE INVENTION 1 provide two antennas having a common centerof symmetry, having equal numbers of homologous elements, havingidentical dimensions when expressed in units of the wavelength at whicheach is to operate. Thus both antennas have identical apertures, andproduce identical beam patterns for a given pattern of phase relationsamong the various elements of each antenna. This property isparticularly desirable in any application (such as the one to bedescribed) in which reliance is placed upon identity of phaserelationships among the elements of each array at its operatingfrequency with those among the elements of the other array at itsoperation frequency.

To cause the receiving array to be effectively phase-steered in thedirection of the information signal band arriving from the transmittingstation, and to cause the transmitting array to be phase-steered in thedirection of a remote receiving station, two phase-reference pilotsignals are provided, adjacent in frequency to the information signalband but with sufficient spacing from it and from each other to permittheir being separated by standard selective filtering techniques. Thefirst, or receiving phase pilot signal, is transmitted from thetransmitting station. It is received by each receiving radiator with theinformation signal, filtered out from the information, and conjugated inphase. The phase-conjugated receiving phase pilot signal is then mixedwith the information signal, producing an information signal which is inphase with the similarly treated information signal from any otherreceiving radiator of the array. A transmitting phase pilot signal istransmitted from the receiving station, received by each receivingradiator and conjugated in phase. The conjugated transmitting phasepilot signal is then mixed with the information signal which haspreviously been mixed with the phase-conjugated receiving phase pilotsignal. This process shifts the phase of the information signal so thatwhen, after suitable frequency conversion and amplification, it isapplied to the transmitting radiator which is the homologue of thereceiving radiator at which the information signal and the two phasepilot signals were received, the total radiation from that transmittingradiator and all the other transmitting radiators in the array(similarly connected through processing networks as here described totheir homologues in the receiving array) will be a phasesteered beamdirected in the direction from which the transmitting phase pilot signalarrived.

While the invention requires, in general, that a complete train ofequipment he provided for each receiving radiator and its homologuetransmitting radiator, this requirement is less formidable than it atfirst appears. First, semiconductor circuitry and miniaturizationtechniques permit ready quantity production of small identicalcomponents for production of a quantity of identical trains ofequipment. Secondly, the subdivision of all the functions into functionsof the separate trains of equipment reduces the maximum power requiredto be handled by any single train. Thirdly, the failure of any giventrain of equipment will render ineffective only one radiator in eitherarray, so that randomly occurring equipment failures, even ifindividually catastrophic, will produce only a proportionatedeterioration in the gain of the array, with results which will remaintolerable until a number of such failures have occurred. Thus thisinvention offers the peculiarly high reliability which results whenfailure will predictably be gradual, as distinct from the reliabilityachieved when, by great care, a very high probability of perfectoperation is produced, but the probability of failure, however small, isof total sudden failure.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 represents a view of twoconcentric arrays of radiators according to my invention.

FIG. 2 represents symbolically the block diagrams of known elementsconnected for use to connect a receiving radiator with its homologoustransmitting radiator in the arrays represented in FIG. ll.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 11 represents twoconcentric arrays: a transmitting array of rings l2, 14, 16, and I8, anda receiving array of rings l3, I5, 17, and 19. The rings are merelyreference marks to represent more clearly the position of the radiatorslocated on them, radiators in the transmitting array being representedby the reference letter T, those in the receiving array beingrepresented by the reference letter R. The transmitting and receivingarrays are geometrically similar, but the dimensions of the transmittingarray are 1.5 times the homologous dimensions of the receiving array.Thus if the transmitting array is operated at a wavelength 1.5 timesthat at which the receiving array is operated, it will be identical inits characteristics and parameters with the receiving array, except forpossible effects of cross coupling between the radiators of the twoarrays. These effects are minimized in two ways; the individualradiators are preferably somewhat directive having broad patterns withmaxima in a direction normal to the plane of the figure; and the designcriterion is employed that, if a proposed ring diameter is such that itwould bring a receiving ring close to a transmitting ring, that diameterring is omitted.

The general characteristics of the array may best be explained bydescribing the manner of arriving at the particular embodimentrepresented in FIG. I. Since the minimum practically desirable spacingbetween elements is one-half the longest proposed wavelength, that willbe taken as the unit of measure. Since the chosen ratio of wavelengthfor the two arrays is 3 to 2, the radius of the innermost ring of thereceiving array was chosen as 2 units. The homologous ring of thetransmitting array is thus determined as 3 units; consequently noreceiving array ring of 3 units radius is permissible. The nextpermissible radius for a ring of the receiving array is then 4 units,producing a homologous ring of the transmitting array having a radius of6 units. The S-unit radius is available for the third ring of thereceiving array, creating a homologous 7 .5- unit radius ring in thetransmitting array. No ring between the ti-unit and 7.5-unit radii canbe the minimal distance of one unit from both of these rings;consequently the next available radius for a ring of the receiving arrayis 8.5 units in radius, producing a transmitting array homologue of12.75 units in radius. By a continuation of this approach, it becomesevident that additional receiving array rings of 9.5, 10.5, and 11.5units radius, producing transmitting array homologues of 14.25, 15.75,and 17.25 units radius, are permissible. However, in order to achievereadily a minimization of the coupling between adjacent radiators, it isdesirable to increase the spacing between rings even further than hasbeen established by the procedure thus far followed. This is effected byeliminating alternate rings according to the following tabulation inwhich the radii of the rings eliminated are shown in parentheses:

It should be observed that, because of the three to two ratio oftransmitting array dimensions to receiving array dimensions, the spacingbetween successive transmitting array rings will be 50 percent greaterthan the spacing between corresponding (homologous) receiving arrayrings. This, however, can never permit the retention in the transmittingarray of a ring whose receiving array homologue has been eliminated,since this would destroy the strict geometrical similarity between thetwo arrays.

The number of radiators in a given ring is determined by the samecriteria of spacing as determine the spacing between successive rings.Since the circumference of a ring of radius R units is equal to 2 pi Runits, the maximum number of radiators which can be spaced by at leastunit spacing in such a ring will be very nearly the whole number lessthan, but nearest to 2 pi R. (This approximation neglects the differencebetween the distance along the arc between adjacent radiators and thelength of the chord connecting them.) However, the same reasons whichrecommend the elimination of alternate rings to increase the radialdistance between successive rings also suggest the elimination ofalternate radiators around the circumference of a given ring. The effectof this procedure is as follows:

As in the elimination of alternate rings, the fact that spacing betweenradiators in a given ring of the transmitting array will be 50 percentgreater than in the homologous receiving array ring does not permit theretention of more radiators in the transmitting array ring; there mustbe a one to one relation between receiving and transmitting radiators,with each transmitting radiator lying on the same radius from the centeras its receiving homologue.

Thus there has been described a procedure which results in a pluralarray of radiators arranged in concentric rings, and having thefollowing characteristics:

l. The plural array is made up of a number of individual arrays,geometrically similar, whose linear dimensions are proportional to thenominal wavelength at which the given individual array is intended tooperate.

2. The individual arrays have a common center, and are made up ofradiators arranged in circular rings around the common center.

3. The requirement of geometrical similarity of the various individualarrays leads to the following requirements:

a. The number of rings in each individual array is the same as thenumber of rings in any other individual ary;

b. The radius of a given ring in an individual array is proportional tothe nominal wavelength at which the given individual array is intendedto operate;

c. The radiators in a given ring are equiangularly spaced around itsperiphery;

d. The number of radiators in a given ring of an individual array is thesame as the number of radiators in the homologous ring of any otherindividual array, and a radiator in a given ring of an individual arraylies on the same radius from the center as the homologous radiator inthe homologous ring of any other individual ary;

e. Every radiator in the plural array is spaced from all other radiatorsby at least one-half the longest wavelength at which any individualarray of the plural array is intended to operate.

The radiators actually employed are end-fire helices having a beam widthof 34 degrees (which would correspond to a theoretical gain of slightlymore than 14 db) and a measured gain of 12.5 db. The helix is adesirable form of radiator for this application because of its lack ofpolar selectivity (as contrasted e.g. with a dipole) and its structuralconvenience. However, the invention is applicable to use with anyradiator having similarly suitable parameters.

The structure and underlying philosophy of the dual array has beendescribed. It now remains to consider the application of its properties.

Referring to FIG. 2, a receiving radiator 22 is represented connected toa diplexer 24, which is a frequency-selective filter which passes to abalanced mixer 26 received signals in the band from (in the specificembodiment constructed) 5925 to 6100 megahertz, and diverts to anotherbalanced mixer 26A signals ranging from 6250 to 6425 megahertz. Thereceived signal consists of an information band 175 megahertz wide,extending from 5925 to 6050 megahertz, a receiving phase pilot signal6080 megahertz, and a transmitting phase pilot signal 6100 megacycles.This received signal is mixed, or heterodyned with the output, at 5825megahertz, of local oscillator 28, and the output of balanced mixer 26,which is the difference between the frequency of local oscillator 28 andthe frequency band of the received signals, extending from to 275megahertz, is amplified by amplifier 30. The amplified output ofamplifier 30 contains (as may be confirmed by substraction) aninformation band at a frequency from 100 to megahertz (corresponding to5925 to 6050 megahertz in the received signal), the receiving phasepilot signal at a frequency of 255 megahertz, and the transmitting phasepilot signal at a frequency of 275 megahertz.

It should be noted that, since the output of balanced mixer 26 is theresult of mixing the incoming signal with a local oscillator frequencylower than the frequency of the incoming signal, the phase of thevarious components of the incoming signal appears unchanged in theoutput of balanced mixer 26.

The output of amplifier 30 is fed to a frequency-selective filter,diplexer 32, which separates the information band 100-225 megahertz,feeding it to the input of amplifier 34, and the 255 and 275 megahertzpilot signals, transmitting them to the input of balanced mixer 36.Balanced mixer 36 mixes the 255 and 275 megahertz pilot signals with the325- megahertz output of local oscillator 38, producing differenceoutputs at 50 and 70 megahertz, corresponding respectively to the 275and 255 megahertz inputs to balanced mixer 36. Since the localoscillator 38 is higher in frequency than the frequencies of the 255 and275 megahertz pilot signals at the input to balanced mixer 36, the phaseof the resulting 70 and 50 megahertz pilot signals in the output is theconjugate of their phase at the input. These signals are fed to theinput of amplifier 40, whose amplified output is fed tofrequency-selective filter, diplexer 42, which separates the 50 and 70megahertz conjugated pilot signals, feeding the 70 megahertz conjugatedpilot signal to the balanced mixer 44 and the S0 megahertz conjugatedpilot signal to balanced mixer 46. The 70 megahertz conjugated pilotsignal is mixed with the 650 megahertz output of local oscillator 48,producing a sum output of 720 megahertz, which is amplified by amplifier50. Since this mixing is additive, the phase of the 70 megahertz signalis not altered by the mixing; that is, it is still conjugate. Similarly,the 50 megahertz signal is mixed by balanced mixer 46 with the 650megacycle output of local oscillator 52, producing an output of 700megacycles which is still conjugate in phase. This latter output isamplified by amplifier 54. Since the difference frequencies in theoutputs of balanced mixers 44 and 46 might be close enough to thedesired addition frequencies to require filtering out, it is desirablethat balanced mixers 44 and 46 be doubly balanced mixers, which produceonly a single, sum output. Such mixers are used in the known art asmodulators for single-sideband transmitters. A description of suchmixers appears in the textbook Communications Systems and Techniques" byM. Schwartz, W. R. Bennett, and S. Stein, McGraw-Hill Book Company 1966,at page 188.

The output of amplifier 50, which is the conjugated phase, at 720megahertz, of the receiving pilot signal which was present in theoriginal input signal at 6080 megahertz, is fed to balanced mixer 56where it is mixed with the output of amplifier 34, the 100-225 megahertzinformation signal, producing an additive output of 820-945 megahertz.Since this mixing is additive, it does not produce a new or additionalphase conjugation; but it now becomes necessary to consider in detailwhat this additive output is in fact.

The receiving radiator 22 is only one of the plurality of receivingradiators represented in FIG. 1. Each such receiving radiator, beingdifierently located in space from every other receiving radiator will,in general, receive the information signal in a different phase. Theinformation signal received at each receiving radiator must (afteramplification and frequency conversion) be adjusted in proper phasebefore being fed to the homologous transmitting radiator, so that thetotal array of transmitting radiators will produce a narrow beam aimedin the direction of the transmitting pilot signal. To do this it isnecessary first to adjust the phase of the information signal from eachreceiving radiator to a common reference. Since the components of theinformation signal flicker unpredictably in amplitude and phase as theinformation content changes, the receiving pilot signal is included as aphase reference. It is sufficiently close in the spectrum to theinformation signal so that the relative difference in its phase at thedifferent receiving radiators will be a close approximation to therelative difference in the phase of the information signal components atthe same receiving radiators.

The mixing in balanced mixer 56 of each sinusoidal component of theinformation signal with phase-conjugated receiving pilot signalsubtracts from the sinusoidal component of the information signal thephase of the receiving pilot signal; but, as has just been stated, thisis very nearly the relative difference in phase of the informationsignal component itself. Thus the sinusoidal component of theinformation signal, as it appears in the output of balanced mixer 56,has been adjusted to eliminate the difference in phase between thesinusoidal information component as received at receiving radiator 22and the same component as received and similarly corrected at any otherreceiving radiator in the receiving array represented in FIG. 1. Itshould be observed particularly that any imperfection in theapproximation of the relative phase difference of the receiving pilotsignal to the sinusoidal component of the information signal will appearin all the channels connected to all the receiving radiators, so thatthe sinusoidal information components at the outputs of all the balancedmixer homologous to balanced mixer 56in all the homologous trains ofequipment connected respectively to all the receiving radiators will bein phase with each other. Thus the description has arrived at a resultof producing a received information signal which is in phase with thereceived information signal in every other similar channel connected toevery other receiving radiator.

There now remains the problem of adjusting the phase of the informationsignal so that, when suitably frequency converted and amplified, andapplied to radiator 58, it will be in proper phase, relative to thesignals applied to all the other transmitting radiators in theplurality, to form a phase-steered beam directed in the direction fromwhich the transmitting phase pilot signal was received at 6100megahertz. Now, the transmitting frequency will be markedly differentfrom the frequency at which the transmitting phase pilot signal wasreceived; but, since the ratio of the dimensions of the transmittingarray relative to the receiving array is proportional to the ratio ofthe transmitting wavelength to the receiving wavelength, the relativephase of the transmitting phase pilot signal received at receivingradiator 22 will be an accurate measure of the relative phase requiredat transmitting radiator 58 to produce a phase-steered beam directed inthe direction from which the transmitting phase pilot signal wasreceived. However, the phase of the transmitting phase pilot signal asreceived must be conjugated as applied to the transmitted signal for thefollowing reason: consider the receiving radiator most remote from thesource of the transmitting phase pilot signal. Such receiving radiatorwill be the last to receive a given peak of a given cycle of thetransmitting phase pilot signal, and so the phase of the signal soreceived will lag behind the phase of the signal received at any otherreceiving radiator. But when a signal is transmitted from the homologoustransmitting radiator, since the direction of travel is reversed, itmust be the first to transmit a given peak of a given cycle of thetransmitted signal, and so must lead the phase of the signal transmittedfrom any other transmitting radiator. Hence a lag in phase on receptionmust be converted into a corresponding lead by phase complementing; andit is effected according to the following description.

The output of balanced mixer 56 is fed through a band-pass filter 60 toeliminate any spurious signals resulting e.g. from imperfections in thebalance of the mixer because of slight differences in the supposedlyidentical components used in the mixer. The filtered output from mixer60 is then mixed additively in balanced mixer 62 with the output ofamplifier. Since the output from band-pass filter 60 is the 820-945megahertz information signal (corrected in phase, as has been described)and the output of amplifier 54 is the conjugately phased transmittingpilot signal, at 700 megahertz, the sum output is the information signalat 1520-1645 megahertz, phased conjugately to the phase of thetransmitting phase pilot signal as received at 6100 megahertz. Thisoutput is passed through filter 64 to remove spurious components, andfed to balanced mixer 66, where it is mixed additively with 2280megahertz output of oscillator 68. The output of balanced mixer 66, inthe band 3800-3925 megahertz, is passed through band-pass filter 70 toremove components outside the started band, amplified by amplifier 72,and fed via diplexer 74 to transmitting radiator 58.

To recapitulate, it has been shown thus far how the incoming signal hasbeen adjusted in phase to correct for the difference in time of arrival,or phase, of the signal at different receiving radiator, changed infrequency and amplified, and adjusted in phase to direct radiation fromthe plural of transmitting radiators in the direction from which thereceiving phase pilot signal has arrived.

A parallel train of equipment, similar to that already described withcorresponding components bearing similar reference numbers, butdifferentiated by the addition of the letter A to each designation,appears below that already described. This second train is adapted toreceive from the lower output of diplexer 24 a received signal havinginformation in the band from 6300 to 6425 megahertz, a receiving phasepilot signal at 6270 megahertz, and a transmitting phase pilot signal at6250 megahertz. This is fed to balanced mixer 26A, where it is mixedwith 6525 megahertz output of oscillator 28A.

The difference output is taken from mixer 26A, giving an informationsignal in the band from 100 to 125 megahertz, a receiving phase pilotsignal at 255 megahertz, and a transmitting phase pilot signal at 275megahertz. These are the same frequencies as are occupied by thecorresponding signals in the output of mixer 26. While the taking of thedifference signal from mixer 26A, with oscillator 28A having a frequencyhigher than component of the incoming received signal, will producephase conjugation, this conjugation will be applied to both the pilotsignals and the information signals. Since there is no relative phaseconjugation between the information signal and the pilot signals, thisconjugation produces no effect. After passing through the A designatedchain of apparatus, the information signal from filter 64A arrives atbalanced mixer 66A where it is mixed with the 5720 megahertz output ofoscillator 68A. In this case, too, the difference output of 4075 to 4200megahertz is taken. This, too, will produce a phase conjugation; butsince the same conjugation will occur in every homologous mixer in theapparatus connected to the array, there will be no net effect from thisconjugation.

The oscillators bearing reference numbers 28, 38, 48, 52, and 68 (andtheir cognates 28A, et cetera) determine by their phases the adjustedphase of the received information signal, and the subsequently adjustedphase of that signal. Since it is essential that these adjustments becorrect with respect to phase adjustments performed in cognate trains ofequipment connecting other pairs of receiving and transmittingradiators, it is necessary that the phases of these oscillators beidentical with the phases of corresponding oscillators in the othertrains of equipment. This is most simply effected by having oscillators28, 38, 48, 52, and 68 common to all the trains of equipment.

It is envisaged that the particular embodiment here described would bewell suited to relaying two-way communication between two stations bothlocated within the phase steering capability of the array representedgenerically in FIG. 1, with a first station transmitting information at5925-6050 megahertz with a receiving phase pilot signal at 6080megahertz to permit phase adjustment of the phase of the receivedinformation in the upper train of equipment represented in FIG. 2, andalso transmitting a transmitting phase pilot signal at 6250 megacyclesto permit phase steering back to the first station of informationtransmitted via the lower train of equipment represented in FIG. 2. Asecond station at another location would transmit information at6300-6425 megahertz with a receiving phase pilot signal at 6270megahertz to permit phase adjustment of the received information in thelower train of equipment represented in FIG. 2, and also transmitting atransmitting phase pilot signal at 6100 megacycles to permit phasesteering back to the second station of information transmitted via theupper train of equipment represented in FIG. 2.

It is evident that this proposed use is merely a somewhat arbitrary onesuggested simply because it meets a very common need for simultaneoustwo-way relay communication. Oneway relaying could be achieved by usingonly the upper train of equipment. In that case, the transmittingstation would transmit the appropriate information band and associatedreceiving phase pilot; and the receiving station would transmit only theproper frequency of transmitting phase pilot signal to direct therelayed information back to itself. Another possibility is to employmore than two trains of equipment in parallel, with the diplexers 24 and74 being suitably modified to separate or blend the more than two bandsof signals. It should be observed that so long as the ratio of receivedto transmitted frequencies is the same as the reciprocal of the ratio ofthe physical dimensions of the receiving to the transmitting arrays,

the phasing methods here disclosed will function effectively, althoughthe particular frequencies employed may conceivably be so far from theoptimum operating frequencies for the arrays that the effectiveness ofthe arrays may be diminished. The term: ratio of received to transmittedfrequencies here used is necessarily subject to reasonableinterpretation in view of the fact that bands of the same finite widthare employed for reception and retransmission of information, atdifi'erent places in the spectrum, so that even the ratio of the highedge of the lower edge of the received to the lower edge of the receivedto the lower edge of the transmitted band. The accuracy with which theratio of frequencies approximates the ratio of dimensions will determinehow accurately the phasing to form the transmitted beam can beaccomplished. An old criterion for adequate accuracy in parabolicreflectors was that the surface be within one-eighth wavelength of itsintended location. This would correspond to a tolerance of the samefraction in frequency ratio. More precise requirements for beamformation and steering would, of course, require closer approximation inthe frequency ratio; but both may be regarded as coming within the scopeof the general statement as to reasonable interpretation.

I claim:

1. A phase-steered relay antenna system comprising:

a. a circularly symmetrical receiving array of a plurality of receivingradiators;

b. a circularly symmetrical transmitting array of a plurality oftransmitting radiators, concentric with the receiving array, equal innumber to the plurality of receiving radiators, geometrically similar tothe receiving array; each transmitting radiator being the homologue of areceiving radiator and lying on the same radius from the center ofsymmetry of both arrays as does that receiving radiator; the ratio ofthe distance of each transmitting radiator along the said radius fromthe said center of symmetry to the distance of the receiving radiatorhomologous to the said transmitting radiator along the said radius fromthe said center of symmetry being the same as the ratio of thewavelength to be transmitted to the wavelength to be received;

c. a plurality of equipment trains, one such train being connected toeach receiving radiator, each such train comprising:

first means to adjust the phase of a received information band signalwith respect to the phase of a received receiving phase pilot signal;

second means to adjust the phase of the said received information bandsignal, adjusted with respect to the phase of the said receiving phasepilot signal, with respect to the phase conjugate of a receivedtransmitting phase pilot signal;

third means to convert the frequency of the said received informationband signal to a different frequency for transmission;

fourth means to receive the said received information band signal, afterit has been adjusted in phase with respect to the phase of the receivedreceiving phase pilot signal and with respect to the phase of thereceived transmitting phase pilot signal, and converted in frequency fortransmission, and connect it to the transmitting radiator which is thehomologue of the said receiving radiator;

in which d. the radiators of a first said circularly symmetrical arrayare arranged in first concentric rings;

the radiators of a second said circularly symmetrical array are arrangedin second concentric rings concentric with the said first concentricrings;

the diameters of the said first concentric rings are proportional to theshorter of the wavelength to be transmitted and the wavelength to bereceived;

the diameters of the said second concentric rings are proportional tothe longer of the wavelength to be transmitted and the wavelength to bereceived;

from each other and the spacing between a radiator and its nearestneighbor in the ring is approximately one said longer wavelength;

g. the radiators are unidirectional in gain characteristic, and

are arranged with their directions of maximum gain normal to the planeof the ring of which they form a part.

I l I i

1. A phase-steered relay antenna system comprising: a. a circularlysymmetrical receiving array of a plurality of receiving radiators; b. acircularly symmetrical transmitting array of a plurality of transmittingradiators, concentric with the receiving array, equal in number to theplurality of receiving radiators, geometrically similar to the receivingarray; each transmitting radiator being the homologue of a receivingradiator and lying on the same radius from the center of symmetry ofboth arrays as does that receiving radiator; the ratio of the distanceof each transmitting radiator along the said radius from the said centerof symmetry to the distance of the receiving radiator homologous to thesaid transmitting radiator along the said radius from the said center ofsymmetry being the same as the ratio of the wavelength to be transmittedto the wavelength to be received; c. a plurality of equipment trains,one such train being connected to each receiving radiator, each suchtrain comprising: first means to adjust the phase of a receivedinformation band signal with respect to the phase of a receivedreceiving phase pilot signal; second means to adjust the phase of thesaid received information band signal, adjusted with respect to thephase of the said receiving phase pilot signal, with respect to thephase conjugate of a received transmitting phase pilot signal; thirdmeans to convert the frequency of the said received information bandsignal to a different frequency for transmission; fourth means toreceive the said received information band signal, after it has beenadjusted in phase with respect to the phase of the received receivingphase pilot signal and with respect to the phase of the receivedtransmitting phase pilot signal, and converted in frequency fortransmission, and connect it to the transmitting radiator which is thehomologue of the said receiving radiator; in which d. the radiators of afirst said circularly symmetrical array are arranged in first concentricrings; the radiators of a second said circularly symmetrical array arearranged in second concentric rings concentric with the said firstconcentric rings; the diameters of the said first concentric rings areproportional to the shorter of the wavelength to be transmitted and thewavelength to be received; the diameters of the said second concentricrings are proportional to the longer of the wavelength to be transmittedand the wavelength to be received; e. the diameter of the smallest firstconcentric ring differs from the diameter of the smallest secondconcentric ring by the said longer wavelength; every other firstconcentric ring has a diameter greater by two said longer wavelengthsthan the next smaller ring without regard to which array the nextsmaller ring belongs to; f. the radiators in a first concentric ring areequally spaced from each other and the spacing between a radiator andits nearest neighbor in the ring is approximately one said longerwavelength; g. the radiators are unidirectional in gain characteristic,and are arranged with their directions of maximum gain normal to theplane of the ring of which they form a part.